Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quantas datas de início qualificadas para a confederação Concacaf?
 ###Tabelas: CREATE TABLE summary_of_qualification (summary_of_qualification_id AUTO_INCREMENT PRIMARY KEY, Confederation VARCHAR, Teams started VARCHAR, Teams that have secured qualification VARCHAR, Teams that can still qualify VARCHAR, Teams that have been eliminated VARCHAR, Remaining places in finals VARCHAR, Total places in finals VARCHAR, Qualifying start date VARCHAR, Qualifying end date VARCHAR) CREATE TABLE 2008_draft (2008_draft_id AUTO_INCREMENT PRIMARY KEY, Round INT, Pick VARCHAR, Player VARCHAR, Position VARCHAR, Team VARCHAR) CREATE TABLE current_member_schools (current_member_schools_id AUTO_INCREMENT PRIMARY KEY, School VARCHAR, Location VARCHAR, Enrolment INT, Founded INT, Denomination VARCHAR, Day/Boarding VARCHAR, School Colors VARCHAR) CREATE TABLE [[_|_]] ([[_|_]]_id AUTO_INCREMENT PRIMARY KEY, No INT, Player VARCHAR, Height VARCHAR, Position VARCHAR, Year born INT, Current Club VARCHAR) CREATE TABLE early_broad_gauge_locomotives_for_all_traffic_types (early_broad_gauge_locomotives_for_all_traffic_types_id AUTO_INCREMENT PRIMARY KEY, Class (old) to 1868 VARCHAR, Railway number(s) VARCHAR, Quantity INT, Year(s) of manufacture VARCHAR, Type VARCHAR)  
SELECT COUNT Qualifying start date FROM summary_of_qualification WHERE Confederation = CONCACAF